Switch to 15m slots for tariffs and planner

[Maschga]

Purpose of this PR is to change default 1h slots to 15m slots. This affects:

• tariffs (cost, co2, solar, both coded and templates)
• planner
• ui

We should do this in a way that all internal data structures use 15m slots. For this purpose, tariff data must be converted to 15m slots when received.

We should still supported 1h or 30m tariffs and templates, but provide an option to convert after receive. The output of evcc tariff might potentially be simplified to still show 1h slots where applicable (nice to have).

When we support 1h or 30m inputs, we'll need specific logic for converting them into 15m slots depending on tariff type:

• prices: constant price over all sub-slots
• solar: interpolated power at start of sub-slot
• co2: interpolated co2 load (clarify howto)

Planner depends on tariffs and must be changed in the same step since planner assumes 1h slots.

/cc @naltatis can we please align on co2

[naltatis]

can we please align on co2

I'd say the value is always gCO2e/kWh. So splitting up 1h our datasource would result in slots with the same value as the source. Same thing for price ($CURRENCY/kWh).

[Maschga]

[naltatis]

Wie besprochen schaue ich mir die Visualisierung des Ladeplans an.